Geology
Sequoia National Park contains a significant portion of America's longest mountain range, the Sierra Nevada. Included in the Park's mountainous landscape is the tallest mountain in the contiguous United States, Mt. Whitney, which rises to 14,505 feet (4,421 m) above sea level. The Great Western Divide parallels the Sierran crest. It is the mountains of the Great Western Divide that greet visitors in Mineral King and that can be seen from Moro Rock and the Giant Forest area. Peaks in the Great Western Divide climb to more than 12,000 feet (3,700 m). Between these mountains lie deep canyons, including Tokopah Valley above Lodgepole, Deep Canyon on the Marble Fork of the Kaweah River and deep in the park's backcountry, Kern Canyon, which is more than 5,000 feet (1,500 m) deep for 30 miles (48 km).
Most of the mountains and canyons in the Sierra Nevada are formed in granitic rocks. These rocks, such as granite, diorite and monzonite, formed when molten rock cooled far beneath the surface of the earth. The molten rock was a by-product of a geologic process known as subduction. Powerful forces in the earth forced the landmass under the waters of the Pacific Ocean beneath and below an advancing North American Continent. Super-hot water driven from the subjecting ocean floor migrated upward and melted rock as it went. This process took place during the Cretaceous Period, 100 million years ago. Granitic rocks have speckled salt and pepper appearance because they contain various minerals including quartz, feldspars and micas. Valhalla or the Angel Wings are prominent cliffs that rise above the headwaters of the Middle Fork of the Kaweah River.
While geologists debate the details, it is clear that the Sierra Nevada is a young mountain range, probably not more than 10 million years old. Forces in the earth, probably associated with the development of the Great Basin, forced the mountains to grow and climb toward the sky. During the last 10 million years, at least four periods of glacial advance have coated the mountains in a thick mantle of ice. Glaciers form and develop during long periods of cool and wet weather. Glaciers move through the mountains like slow-motion rivers carving deep valleys and craggy peaks. The extensive history of glaciation within the range and the erosion resistant nature of the granitic rocks that make up most of the Sierra Nevada have together created a landscape of hanging valleys, waterfalls, craggy peaks, alpine lakes and glacial canyons.
Park caves, like most caves in the Sierra Nevada of California, are mostly solutional caves dissolved from marble. Marble rock is essentially limestone that was metamorphosed by the heat and pressure of the formation and uplift of the Sierra Nevada Batholith. The batholith's rapid uplift over the past 10 million years led to a rapid erosion of the metamorphic rocks in the higher elevations, exposing the granite beneath; therefore, most Sierra Nevada caves are found in the middle and lower elevations (below 7,000 ft/2,100 m), though some caves are found in the park at elevations as high as 10,000 ft (3,000 m) such as the White Chief cave and Cirque cave in Mineral King. These caves are carved out of the rock by the abundant seasonal streams in the park; most of the larger park caves currently have or have had sinking streams running through them.
The park is home to over 240 known caves, and potentially hundreds more. The caves in the park include California's longest cave at over 20 miles (32 km), Lilburn Cave, as well as recently discovered caves that remain strictly off-limits to all but a handful of specialists who visit on rare occasions to study cave geology and biology. The only commercial cave open to park visitors remains Crystal Cave, the park's second-longest at over 3.4 miles (5.5 km) and remarkably well-preserved for the volume of visitation it receives annually. It was discovered on April 28, 1918 by Alex Medley and Cassius Webster. The cave is a constant 48 °F (9 °C), and only accessible by guided tour.
Caves are discovered every year in the park; in fact, 17 have been discovered since 2003 alone. The most recently discovered major cave in the park, in September 2006, has been named Ursa Minor. Park caves are valued by scientists and cavers alike for their pristine beauty, variety, and endemic cave life.
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